We develop a weak coupling approach to superconductivity in twisted bilayer graphene, starting from the Fermi liquid regime. A key observation is that near half filling, the fermiology consists of well nested Fermi pockets derived from opposite valleys, leading to enhanced valley fluctuation, which ...
Here we use scanning tunnelling microscopy and spectroscopy to visualize the local density of states and charge distribution in magic-angle twisted bilayer graphene. Doping the sample to partially fill the flat band, we observe a pseudogap phase accompanied by a global stripe charge order that ...
Tunable second harmonic generation in twisted bilayer graphene. Matter 3, 1361–1376 (2020). Article Google Scholar Kim, C.-J. et al. Stacking order dependent second harmonic generation and topological defects in h-BN bilayers. Nano Lett. 13, 5660–5665 (2013). Article ADS Google Scholar ...
We study the impact of Coulomb interactions at half-integer filling of the moiré Chern bands of twisted double-bilayer graphene and twisted mono-bilayer graphene, using unbiased exact diagonalization complemented by unrestricted Hartree-Fock calculations. For small intra-sublattice tunneling, w_{AA} ...
The flat bands that appear in some twisted van der Waals heterostructures provide a setting in which strong interactions between electrons lead to a variety of correlated phases1–20. In particular, heterostructures of twisted double bilayer graphene host correlated insulating states that can be tuned...
Superconductivity in twisted bilayer graphene has attracted much attention in recent years. Based on the significant experimental facts, there are many theoretical investigations on its superconducting mechanism and pairing symmetry. In this paper, we study the theory of the electron-phonon coupling in ...
We attribute these large values to the large magnitude of the characteristic magnetization of individual Bloch states, which we find to reflect the fast Dirac velocity of single-layer graphene, rather than the slow velocity of the twisted bilayer. These large values are forced to mutually cancel ...
Spontaneous symmetry breaking and topology in twisted bilayer graphene: the nature of the correlated insulating states and the quantum anomalous Hall effectJianpeng LiuXi DaiAmerican Physical Society
This four-electron condensate, instead of superconductivity, shows a spontaneous breaking of time-reversal symmetry. Our results suggest that twisted bilayer graphene is an especially promising platform to study different types of condensates, beyond the pair-condensate paradigm....
Observation of superconductivity in twisted-bilayer-graphene and highly-oriented-pyrolytic-graphite (HOPG) for certain magic-angles-of-rotation has recently attracted an important attention. Unusual temperature-(T)-induced-shifts in the graphitic c-axis have also been reported in HOPG in conditions of...